Novel plasma in-situ DRIFTS reaction tank

Abstract

The invention discloses a novel plasma in-situ DRIFTS reaction tank which comprises a base provided with an accommodating cavity; the dome is made of a metal material, is connected to the power supply grounding electrode and is arranged on the base to form a reaction space; the sample pool is positioned in a reaction space formed by the base and the dome, is connected with the gas outlet connector and is provided with a catalyst; the high-voltage electrode is positioned in the air outlet, and one end of the high-voltage electrode is buried in the sample cell; the at least three optical windows are arranged on the dome and face the sample cell; the spectrograph is connected to one side of the base; reaction gas enters from the gas inlet connector and sequentially passes through the gas inlet, the reaction space, the sample pool, the gas outlet and the gas outlet connector, and organic unification of uniform electric field distribution, stable plasma discharge and high-quality in-situ spectral analysis is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of catalytic chemistry and spectral analysis, and in particular to a novel plasma in-situ DRIFTS reaction pool. Background Art

[0002] In the field of catalytic chemistry research, in-situ analytical techniques are essential for understanding reaction mechanisms and optimizing catalyst performance. Among them, diffuse reflectance infrared spectroscopy (DRIFTS), as a non-invasive characterization method that can monitor species changes on the catalyst surface in real time, has become an important tool for catalytic research. However, with the rise of plasma-assisted catalytic technology, traditional DRIFTS reaction cell design faces new challenges.

[0003] First, electrode design becomes a key issue. In traditional designs, the electrode layout is often too compact or the spatial distribution is unreasonable, resulting in uneven electric field distribution, affecting the stability and uniformity of the plasma. This will not only interfere with the catalytic reaction, but may also cause distortion of the spectral signal.

[0004] Secondly, temperature control in a plasma environment is also a challenge. Plasma discharge generates additional heat, and how to ensure precise control of the reaction temperature while avoiding cell overheating becomes a thorny issue.

[0005] In addition, the traditional design has the following problems: 1) The risk of electrical breakdown is high, affecting equipment safety and experimental reliability; 2) The plasma discharge intensity is difficult to control and may be too strong to damage the catalyst, or too weak to affect the reaction efficiency; 3) The electrode arrangement may block the infrared light path and reduce the spectral quality; 4) Filamentary discharge may cause catalyst particles to fly away, interfering with the experiment; 5) The discharge pattern is unstable, resulting in fluctuations in reaction conditions. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a novel plasma in-situ DRIFTS reaction cell, which realizes the organic unity of uniform electric field distribution, stable plasma discharge and high-quality in-situ spectral analysis, and meets the requirements of plasma environment and in-situ DRIFTS analysis.

[0007] The present invention adopts the following technical solutions:

[0008] A novel plasma in-situ DRIFTS reaction cell comprises: a base, which has a containing cavity, a gas inlet connection port and a gas outlet connection port on the side, a gas outlet connected to the gas outlet connection port on the bottom surface, and a gas inlet connected to the gas inlet connection port in the containing cavity; a dome, which is made of metal material, connected to a power grounding electrode, and arranged on the base to form a reaction space; a sample cell, which is located in the reaction space formed by the base and the dome, connected to the gas outlet connection port, and provided with a catalyst; a high-voltage electrode, which is located in the gas outlet port and has one end buried in the sample cell; at least three optical windows, which are arranged on the dome and face the sample cell; a spectrometer, which is connected to one side of the base; a reaction gas enters from the gas inlet connection port, and passes through the gas inlet port, the reaction space, the sample cell, the gas outlet port, and the gas outlet connection port in sequence.

[0009] Preferably, the air inlet connection port is connected to the air inlet port to form an air inlet passage, and the air outlet connection port is connected to the air outlet port to form an air outlet passage.

[0010] Preferably, the sample pool has a catalyst support structure in which a catalyst is arranged; the sample pool has a diameter of 10-20 mm and a depth of 2-5 mm; the catalyst is evenly distributed in the sample pool by vibration of a certain frequency, and a quartz sand layer is provided above the catalyst to prevent the catalyst particles from flying under the action of a strong electric field.

[0011] Preferably, the infrared light enters from an optical window, is reflected at the sample cell, and then exits from another optical window.

[0012] Preferably, the optical window is made of ZnSe or KBr, with a diameter of 15-25 mm and a thickness of 2-4 mm; the angle between the optical window and the horizontal plane is 55-60 degrees, and a graphite gasket is used to seal the optical window and the dome, with a thickness of 0.1-0.2 mm; heating wires are arranged around the optical window.

[0013] Preferably, the base is made of high-performance dielectric material with a diameter ranging from 30-50mm and a height of 20-30mm. The dome is made of stainless steel or gold-plated material with a diameter matching the base and a height of 20-30mm. The base and the dome cooperate to form an overall structure with a height of 40-60mm.

[0014] Preferably, the high-voltage electrode is made of platinum, tungsten or 316L stainless steel, with a diameter of 0.5-1.5 mm and a length of 30-50 mm; an insulating sleeve is provided on the surface of the high-voltage electrode; the top of the high-voltage electrode is 3-5 mm below the catalyst surface and deviates from the central axis of the sample cell by 0.5-1 mm.

[0015] Preferably, the high-voltage electrode adopts a spherical or hemispherical electrode head with a diameter of 1.5-2.5 mm; the surface of the high-voltage electrode is treated by micron-level plasma spraying to form a porous structure with a thickness of 10-50 μm.

[0016] Preferably, the dome has a thickness of 2-4 mm and the inner surface is electrochemically polished or plasma sprayed.

[0017] Preferably, a spiral gas distribution groove is designed inside the reaction pool, with a width of 0.5-1 mm and a depth of 0.5-1 mm; a miniature photoelectric detector is arranged inside the reaction pool.

[0018] Preferably, a dome limiting groove matching the dome is provided in the base, an O-ring groove is provided in the dome limiting groove, and a high-temperature and pressure-resistant O-ring is provided in the O-ring groove.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1. Prevent electrical breakdown: Optimize the thickness of the dielectric layer. Use high-insulation-strength PEK material (breakdown strength>20kV / mm) as the base, with a thickness of not less than 5mm. Set an insulating sleeve around the high-voltage electrode, made of alumina ceramic, with a thickness of 1-2mm to further improve the insulation performance. In addition, add a fast-response overvoltage protection device in the external circuit, with a response time of <1μs, to prevent instantaneous high voltage from damaging the system.

[0021] 2. Prevent the plasma discharge from being too weak: Optimize the discharge intensity by precisely controlling the exposed length of the high-voltage electrode (adjustable 1-5mm). Design adjustable power supply parameters, including voltage (0-30kV), frequency (50Hz-20kHz) and waveform (sine wave, square wave, pulse wave, etc.). Introduce an adaptive power control system to automatically adjust the output power according to the real-time monitored discharge parameters to ensure that the discharge intensity is always maintained at the optimal level. At the same time, a miniature photodetector with a diameter of 0.5mm is set inside the reaction pool to monitor the discharge intensity in real time and provide feedback signals for power control.

[0022] 3. Prevent the high-voltage electrode arrangement from blocking the laser path: Carefully design the position and angle of the high-voltage electrode to ensure that it does not interfere with the infrared light path. The top of the high-voltage electrode is 3-5mm away from the catalyst surface and slightly deviates from the central axis by 0.5-1mm. The incident and reflected light paths are optimized through optical simulation software, and the incident angle can be adjusted within the range of 30-60 degrees to maximize the effective signal. A micro-reflector with a diameter of 2-3mm is set inside the reaction cell, which can be fine-tuned by ±5 degrees to further optimize the light path.

[0023] 4. Preventing catalyst blow-off caused by filamentary discharge: This design mainly eliminates the generation of filamentary discharge by optimizing the electrode configuration and discharge parameters. Specific measures include: using spherical or hemispherical electrode heads with a diameter of 1.5-2.5mm to reduce electric field concentration. Micron-level plasma spraying treatment is performed on the surface of the high-voltage electrode to form a porous structure with a thickness of 10-50μm to promote uniform discharge. Using a pulse power supply with a pulse width of 1-10μs and a repetition frequency of 1-10kHz can effectively suppress the formation of filamentary discharge. Optimizing gas flow and maintaining a certain gas flow rate (10-50cm / s) will help suppress the development of filamentary discharge.

[0024] 5. Restore the discharge characteristics of the DBD reactor: The electric field distribution and discharge characteristics of the industrial DBD reactor are simulated through the carefully designed electrode configuration and dielectric layer arrangement. The distance between the high-voltage electrode and the dome can be adjusted in the range of 5-10mm, and the thickness of the dielectric layer is 0.5-2mm. High-speed camera technology (frame rate>10000fps) and optical emission spectroscopy technology (spectral range 200-900nm, resolution <0.1nm) are used to monitor and adjust the discharge mode in real time. An intelligent control algorithm is introduced to automatically adjust the power supply parameters according to the real-time monitoring data to ensure the consistency of the discharge characteristics with the actual DBD reactor. In addition, replaceable electrode and dielectric modules are designed with a diameter of 10-20mm and a thickness of 1-5mm to simulate different types of DBD reactor configurations. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the overall structure of the reaction pool.

[0026] Figure 2 Schematic diagram of the cross-sectional structure of the reaction tank.

[0027] Figure 3 Schematic diagram of the external structure of the reaction pool.

[0028] Figure 4 Schematic diagram of the explosion structure of the reaction pool.

[0029] Figure 5 This is a schematic diagram of the cross-sectional structure of the reaction pool from another perspective.

[0030] Figure 6 A partial cross-sectional view of the base Figure 1 .

[0031] Figure 7 A partial cross-sectional view of the base Figure 2 .

[0032] Figure 8 Schematic diagram of the reaction pool workflow.

[0033] In the figure, base 1, air inlet connection port 1-1, air outlet connection port 1-2, air outlet 1-3, air inlet 1-4, dome limiting groove 1-5, O-ring groove 1-6, spectrometer limiting column 1-7, spectrometer limiting groove 1-8, dome 2, sample cell 3, catalyst support structure 3-1, high voltage electrode 4, optical window 5. DETAILED DESCRIPTION

[0034] In order to facilitate the understanding of the technical solution of the present invention, a detailed description is given below in conjunction with the accompanying drawings and specific embodiments.

[0035] like Figure 1-Figure 7 As shown, a novel plasma in-situ DRIFTS reaction cell comprises a base 1, a dome 2, a sample cell 3, a high voltage electrode 4, an optical window 5 and a spectrometer;

[0036] Among them, Figure 1 As shown, the reaction cell body is mainly composed of a base 1 and a dome 2, and the base 1 is made of high-performance dielectric materials such as polyether ketone (PEK), with excellent heat resistance, chemical corrosion resistance and high dielectric strength. The diameter range of the base 1 is 30-50mm, and the height is 20-30mm. The dome 2 is made of stainless steel or gold-plated material, and the diameter matches the base, and the height is 20-30mm. The base 1 and the dome 2 are fixedly connected by 6-8 evenly distributed M3-M5 screws to form an airtight reaction space. The overall structure is preferably 40-60mm in height, which ensures enough reaction space and optical path length. This design not only ensures structural stability, but also lays the foundation for uniform electric field distribution.

[0037] Specifically, Figure 1 , Figure 6-Figure 7 As shown, the base 1 has an accommodating cavity in the middle, an air inlet connection port 1-1 and an air outlet connection port 1-2 on the side, an air outlet port 1-3 connected to the air outlet connection port 1-2 on the bottom, and an air inlet port 1-4 connected to the air inlet connection port 1-1 in the accommodating cavity; the air inlet connection port 1-1 is connected to the air inlet port 1-4 to form an air inlet channel, and the air outlet connection port 1-2 is connected to the air outlet port 1-3 to form an air outlet channel;

[0038] The dome 2 is connected to the power grounding electrode and is disposed on the base 1 ; the dome 2 covers the base 1 to form a reaction space.

[0039] This application innovatively uses dome 2 directly as a ground electrode, which simplifies the structural design, reduces additional grounding components, and ensures the uniformity of the electric field. Since the ground electrode of the plasma driving power supply already has a good grounding setting, dome 2 is actually indirectly connected to the earth by connecting to the power supply ground electrode. This grounding method ensures the electrical safety of the entire system and effectively prevents static electricity accumulation and potential risks of electric shock. Directly using dome 2 as a ground electrode not only simplifies the structure, but also helps to maintain the uniformity of the electric field in the reaction area, which is crucial to the stability of the plasma. This design scheme not only ensures the necessary grounding effect, but also avoids additional grounding lines, improving the overall reliability and operational flexibility of the system.

[0040] In addition, the inner surface of the dome 2 is specially treated, such as electrochemical polishing or plasma spraying, to enhance its conductivity and corrosion resistance. The thickness of the dome is 2-4 mm, which ensures mechanical strength without excessively increasing the overall weight.

[0041] The inlet connection port 1-1 is set on the side of the base 1, with a diameter of 1-2mm, and is connected to the external gas pipeline through a micro quick connector. The inner diameter of the gas outlet 1-3 is 0.5-1mm, which is connected to the catalyst on the sample pool 3 to ensure that the gas flows evenly through the catalyst layer. A spiral gas distribution groove is designed inside the reaction pool, with a width of 0.5-1mm and a depth of 0.5-1mm to optimize the gas distribution. The gas flow rate can be adjusted in the range of 10-100mL / min and is accurately controlled by a mass flow controller. This design ensures sufficient contact between the reaction gas and the catalyst and improves the reaction efficiency.

[0042] The base 1 is provided with a dome limiting groove 1-5 matching the dome 2, and the dome limiting groove 1-5 is provided with an O-ring groove 1-6, and the O-ring groove 1-6 is provided with a high temperature and pressure resistant O-ring. The material of the O-ring is fluororubber (FKM) or perfluoroether rubber (FFKM), and the cross-sectional diameter is 1.5-2.5mm. The depth of the O-ring groove 1-6 is 1.2-2.0mm, and the width is 2.0-3.0mm, which can ensure the good sealing of the reaction pool in the temperature range of -40°C to 250°C and the pressure of 0-5bar. At key sealing locations, such as around the optical window 5, a double O-ring design is used to further improve the sealing reliability.

[0043] The sample pool 3 is located in the reaction space formed by the base 1 and the dome 2, connected to the gas outlet connection port 1-4, and provided with a catalyst. The diameter of the sample pool 3 is 10-20 mm and the depth is 2-5 mm. The catalyst loading is preferably 50-200 mg, which is adjusted according to the catalyst density and reaction requirements. To ensure the uniformity of the loading, a vibration compaction technology can be used with a vibration frequency of 50-100 Hz and a time of 10-30 seconds. In addition, a layer of 100-200 mesh quartz sand with a thickness of 0.5-1 mm can be covered on the top of the catalyst layer to prevent the catalyst particles from flying under the action of a strong electric field.

[0044] like Figure 4-Figure 5 The high-voltage electrode 4 is located in the gas outlet 1-3 and one end is buried in the catalyst of the sample pool 3; the high-voltage electrode 4 is inserted from the gas outlet 1-3 at the bottom of the base 1 and buried in the catalyst. The diameter of the high-voltage electrode 4 is preferably 0.5-1.5 mm, and the length is adjusted according to the height of the reaction pool, usually 30-50 mm. The top of the high-voltage electrode 4 is 3-5 mm below the catalyst surface. This distance ensures uniform electric field distribution and avoids interference with the light path.

[0045] First, if the top of the high-voltage electrode 4 is flush with the catalyst surface or exceeds the catalyst surface, a tip effect may occur, that is, the electric field near the high-voltage electrode 4 is too concentrated, resulting in an uneven electric field. This effect can cause local electric field enhancement, which in turn leads to non-uniform plasma distribution, affecting the uniformity of the reaction. Therefore, placing the top of the high-voltage electrode 4 slightly below the catalyst surface (3-5mm distance) can avoid this electric field concentration effect and make the electric field more evenly distributed on the catalyst surface and inside. In addition, through the above-mentioned buried design, the electric field below the high-voltage electrode 4 can be evenly extended through the catalyst to ensure the consistency of the electric field inside the catalyst material. It is crucial for plasma-coupled reactions because uniform electric field distribution can ensure that the catalyst surface and the internal reactive active area are uniformly excited by plasma, thereby improving reaction efficiency and consistency.

[0046] Second, in the DRIFTS (Diffuse Reflectance Infrared Fourier Transform Spectroscopy) experiment, the path design of infrared light is very important to ensure that light can pass through the catalyst and perform effective spectral measurements. Any object that may block or scatter infrared light will interfere with the spectral signal and affect the experimental results. The DRIFTS experiment relies on infrared light irradiating the catalyst surface and collecting its reflection spectrum. If the top of the high-voltage electrode 4 protrudes from the catalyst surface, it may directly interfere with the transmission or reflection of infrared light, resulting in the blocking or scattering of the light path. In this application, the design of the top of the high-voltage electrode 4 being 3-5mm lower than the catalyst surface can "hide" the high-voltage electrode 4 under the catalyst layer, avoiding the infrared light being directly reflected or blocked by the electrode. In addition, if the electrode is designed too close to the catalyst surface, it may absorb or scatter part of the infrared light, thereby interfering with the DRIFTS signal. By properly burying the top of the high-voltage electrode 4 into the catalyst, the absorption and scattering of infrared light by the high-voltage electrode 4 can be reduced, thereby ensuring the integrity of the light path and ensuring the accuracy of the DRIFTS signal.

[0047] Third, the interaction between the electric field distribution and the optical path needs to be carefully designed, especially in the DRIFTS experiment of plasma-coupled reactions. If the electric field is too concentrated on the catalyst surface, it may cause excessively strong plasma discharges, resulting in arcs or overheating, affecting the reaction uniformity on the catalyst surface, or even damaging the catalyst surface. The top of the high-voltage electrode 4 is located a few millimeters below the catalyst, which can prevent this concentrated discharge, ensure the uniform distribution of the electric field, and reduce the side effects of the reaction. In addition, the position and design of the high-voltage electrode 4 must not only ensure a uniform electric field in the reaction zone, but also must avoid interfering with the path of infrared light in the experiment. By burying the high-voltage electrode 4 under the catalyst, effective plasma excitation can still be provided without affecting the optical path.

[0048] Preferably, in actual use, the electrode can be fine-tuned by ±2 mm in the vertical direction to optimize the discharge effect.

[0049] The high-voltage electrode 4 is made of corrosion-resistant materials such as platinum, tungsten or 316L stainless steel, with a diameter of 0.5-1.5mm and a length of 30-50mm. The above materials not only have excellent conductivity, but also remain stable in various reaction atmospheres. The dome 2 (ground electrode) can be made of 304 or 316L stainless steel, or gold-plated on a stainless steel substrate (gold layer thickness 0.5-2μm) to improve its corrosion resistance and conductivity. The high-voltage electrode 4 is connected to the external high-voltage power supply through a special interface at the bottom, and the interface uses ceramic-metal sealing technology to ensure high-voltage insulation. The voltage range is 0-30kV, the current is 0-100mA, and the frequency is adjustable (50Hz-20kHz). The dome 2 (ground electrode) is connected to the ground wire through a special grounding bolt with a diameter of 3-5mm, and the grounding resistance is <0.1Ω. All electrical connections are shielded to reduce electromagnetic interference.

[0050] like Figure 2-Figure 3 As shown, at least three optical windows 5 are arranged on the dome 2, facing the sample pool 3; taking three optical windows 5 as an example, the material of the optical window 5 can be ZnSe or KBr, with a diameter of 15-25mm and a thickness of 2-4mm. The installation angle of the optical window 5 is optimized, usually with an angle of 55-60 degrees with the horizontal plane, to ensure the best infrared light incident and reflection effect. A graphite gasket is used to seal the optical window 5 and the dome 2, with a thickness of 0.1-0.2mm. To prevent condensation on the surface of the optical window 5, a heating wire can be set around the window, with a power of 1-3W, and the temperature can be controlled at 40-60°C.

[0051] The spectrometer is connected to one side of the base 1. One side of the base 1 is provided with a spectrometer limiting column 1-7 and a spectrometer limiting groove 1-8 for connecting and installing the spectrometer, and the spectrometer is preferably an infrared spectrometer.

[0052] In this application, the base 1 is made of PEK material with high insulation strength (breakdown strength>20kV / mm) and a thickness of not less than 5mm. An insulating sleeve is set around the high-voltage electrode 4, and the material is alumina ceramic with a thickness of 1-2mm to further improve the insulation performance. In addition, a fast-response overvoltage protection device is added to the external circuit, and the response time is <1μs to prevent instantaneous high voltage from causing damage to the system.

[0053] In the present application, the discharge intensity is optimized by precisely controlling the exposed length of the high-voltage electrode 4 (adjustable 1-5mm). Adjustable power supply parameters are designed, including voltage (0-30kV), frequency (50Hz-20kHz) and waveform (sine wave, square wave, pulse wave, etc.), and the above power supply parameters can be selected by the user when in use. An adaptive power control system is introduced to automatically adjust the output power according to the discharge parameters monitored in real time to ensure that the discharge intensity is always maintained at an optimal level. At the same time, a miniature photodetector with a diameter of 0.5mm is set inside the reaction cell to monitor the discharge intensity in real time and provide a feedback signal for power control.

[0054] In this application, the position and angle of the high-voltage electrode 4 are carefully designed to ensure that the infrared light path is not interfered with. Infrared light enters from the optical window 5, reflects at the catalyst on the sample cell 3, and exits from another optical window 5. The top of the high-voltage electrode 4 is 3-5mm away from the catalyst surface and slightly deviates from the central axis of the sample cell 3 by 0.5-1mm. The incident and reflected light paths are optimized by optical simulation software, and the incident angle can be adjusted within the range of 30-60 degrees to maximize the effective signal. A micro-reflector with a diameter of 2-3mm can also be set inside the reaction cell, which can be fine-tuned by ±5 degrees to further optimize the light path.

[0055] In this application, the generation of filamentary discharge is eliminated by optimizing the electrode configuration and discharge parameters. Specific measures include: using spherical or hemispherical electrode heads with a diameter of 1.5-2.5mm to reduce electric field concentration. Micron-level plasma spraying is performed on the surface of the high-voltage electrode 4 to form a porous structure with a thickness of 10-50μm to promote uniform discharge. A pulse power supply is used with a pulse width of 1-10μs and a repetition frequency of 1-10kHz to effectively suppress the formation of filamentary discharge. Optimizing gas flow and maintaining a certain gas flow rate (10-50cm / s) helps to suppress the development of filamentary discharge.

[0056] In this application, the electric field distribution and discharge characteristics of an industrial DBD reactor are simulated by carefully designed electrode configurations and dielectric layer arrangements. The electrode spacing can be adjusted in the range of 3-10 mm, and the dielectric layer thickness is 0.5-2 mm. High-speed camera technology (frame rate>10000fps) and optical emission spectroscopy technology (spectral range 200-900nm, resolution <0.1nm) are used to monitor and adjust the discharge mode in real time. An intelligent control algorithm is introduced to automatically adjust the power supply parameters according to real-time monitoring data to ensure the consistency of the discharge characteristics with the actual DBD reactor. In addition, replaceable electrodes and dielectric modules are designed with a diameter of 10-20 mm and a thickness of 1-5 mm to simulate different types of DBD reactor configurations.

[0057] As a preferred method, according to the Faraday cage principle, a metal shielding layer is added to the outside of the reaction pool to reduce external electromagnetic interference. At the same time, all signal lines use high-quality shielded cables to improve the accuracy of data collection.

[0058] As a preferred method, the reaction pool components use standardized interfaces for easy disassembly and replacement. Optical windows of different materials and electrodes of various specifications can be quickly replaced according to experimental requirements, improving the versatility and practicality of the equipment.

[0059] As a preferred method, multiple safety protection mechanisms are integrated, including overvoltage protection, overcurrent protection, overtemperature protection, etc. An emergency cut-off switch is provided to quickly shut down the high voltage power supply and heating system in abnormal situations.

[0060] The working principle of the present invention integrates plasma technology, catalytic chemistry and spectral analysis, and realizes real-time, in-situ monitoring of catalytic reactions in a plasma environment. Through precisely controlled plasma discharge, effective use of catalyst active sites, highly sensitive spectral analysis and precise gas flow control, this device provides a powerful experimental platform for studying the mechanism of plasma-assisted catalytic reactions. The specific working principles include:

[0061] 1. Plasma generation: A high voltage is applied between the high voltage electrode 4 and the ground electrode (dome) to generate plasma discharge in the catalyst region.

[0062] 2. Catalytic reaction: Plasma activates the reactants and catalytic reaction occurs on the catalyst surface.

[0063] 3. Spectral analysis: Infrared light is irradiated onto the catalyst through a window, and the reflected light is collected and analyzed to monitor surface species in real time.

[0064] 4. Gas flow: The reaction gas enters from the bottom, passes through the discharge area and catalyst filling area inside the dome, and is discharged from the gas outlet channel arranged on the base.

[0065] Example 1

[0066] CO2 hydrogenation reaction to produce methane:

[0067] 100 mg of Ni / Al2O3 catalyst was loaded into the reaction cell. The reaction temperature was set to 300°C and controlled by a water circulation heating system. The voltage of the high voltage electrode 4 was set to 15 kV and the frequency was 10 kHz. A mixture of H2 and CO2 (H2:CO2=4:1) was introduced with a total flow rate of 50 mL / min. The plasma discharge and DRIFTS system were started to monitor the changes in species on the catalyst surface in real time.

[0068] 1.DRIFTS spectrum acquisition:

[0069] A Fourier transform infrared spectrometer equipped with an MCT detector was used. The spectral resolution was set to 4 cm -1 The number of scans was 32 times / spectrum. A spectrum was collected every 30 seconds for the entire reaction process.

[0070] 2. Background spectrum:

[0071] Before the reaction gas is introduced, a background spectrum of the catalyst is collected under a pure nitrogen atmosphere. This background spectrum is used for subsequent spectra processing to highlight the changes during the reaction.

[0072] 3. Data processing:

[0073] Use professional spectral software (such as OPUS or OMNIC) for real-time data processing, and perform background subtraction, baseline correction and normalization on the collected spectra.

[0074] 4. Characteristic peak analysis:

[0075] Focus on CO2 (2349cm -1 )、CH4(3015cm -1 )、CO(2143cm -1 ) and other key species. Monitoring surface adsorption such as HCOO-(1590cm -1 )、CO32-(1420cm -1 ) and other intermediates.

[0076] 5. Visualization of dynamic changes:

[0077] Use 3D waterfall plots to show the evolution of spectra over time. Plot the peak intensity of key species over time.

[0078] 6. In-situ calibration:

[0079] Introduce standard gas of known concentration into the reaction system to establish a quantitative relationship between peak intensity and concentration.

[0080] 7. Data synchronization:

[0081] The DRIFTS data are synchronized with the online gas chromatography or mass spectrometry data at the reactor outlet to achieve correlation analysis of gas phase and surface species. Through these methods, we can comprehensively and in real time monitor the dynamic changes of catalyst surface species, providing direct experimental evidence for a deep understanding of the reaction mechanism. This in situ characterization technology combined with plasma-assisted catalysis provides a unique perspective for studying CO2 hydrogenation reactions. The results show that under plasma assistance, the CO2 hydrogenation rate is significantly improved, and the CH4 generation rate is 3 times higher than that of conventional thermal catalysis. The DRIFTS spectrum clearly shows the evolution of the reaction intermediates, providing an important basis for the study of the reaction mechanism.

[0082] Example 2

[0083] N2 hydrogenation reaction:

[0084] 100 mg Fe-K catalyst was used, and the reaction temperature was set to 450°C. The high voltage electrode voltage was 20 kV and the frequency was 15 kHz. A mixed gas of N2 and H2 (N2:H2=1:3) was introduced with a total flow rate of 80 mL / min. DRIFTS results showed that the introduction of plasma significantly promoted the activation of the N≡N triple bond, the peak intensity of the surface adsorbed N species increased by 5 times compared with conventional thermal catalysis, and the generation rate of NH3 increased by 2.5 times.

[0085] Comparative example: Reference patent CN210533973U

[0086] The reaction cell described in the patent was used to carry out CO2 hydrogenation reaction. The results showed that due to the limitations of the electrode design, the plasma distribution was uneven, resulting in large differences in the reaction activity of the catalyst surface. The DRIFTS signal quality was poor, and it was difficult to accurately identify surface intermediates. In addition, due to the limitations of the temperature control system, the reaction temperature fluctuated greatly (±10°C), affecting the repeatability of the experiment. In contrast, the reaction cell of the present invention shows obvious advantages in plasma uniformity, spectral signal quality and temperature control accuracy, providing a more reliable and accurate experimental platform for plasma-assisted catalysis research.

[0087] The above are only preferred embodiments of the present invention. The protection scope of the present invention shall be based on the scope defined by the claims. Several improvements and modifications made by those skilled in the art without departing from the spirit and scope of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A novel plasma in-situ DRIFTS reaction cell, characterized in that: include: A base (1) having a receiving cavity, an air inlet connection port (1-1) and an air outlet connection port (1-2) on a side surface, an air outlet port (1-3) in communication with the air outlet connection port (1-2) on a bottom surface, and an air inlet port (1-4) in communication with the air inlet connection port (1-1) in the receiving cavity; The dome (2) is made of metal material, connected to the power grounding electrode, and arranged on the base (1) to form a reaction space; The sample pool (3) is located in the reaction space formed by the base (1) and the dome (2), connected to the gas outlet connection port (1-4), and is provided with a catalyst; A high voltage electrode (4) is located in the gas outlet (1-3) and one end of which is buried in the catalyst of the sample pool (3); at least three optical windows (5) are arranged on the dome (2) and are arranged toward the sample pool (3); A spectrometer connected to one side of the base (1); The reaction gas enters from the gas inlet connection port (1-1), and passes through the gas inlet port (1-4), the reaction space, the sample pool (3), the gas outlet port (1-3) and the gas outlet connection port (1-2) in sequence.

2. The novel plasma in-situ DRIFTS reaction cell according to claim 1 is characterized in that: The air inlet connection port (1-1) is connected to the air inlet port (1-4) to form an air inlet passage, and the air outlet connection port (1-2) is connected to the air outlet port (1-3) to form an air outlet passage.

3. The novel plasma in-situ DRIFTS reaction cell according to claim 1 is characterized in that: The sample pool (3) has a catalyst support structure (3-1) in it, and a catalyst is arranged in the catalyst support structure (3-1); the sample pool (3) has a diameter of 10-20 mm and a depth of 2-5 mm; The catalyst is evenly distributed in the sample pool (3) through vibration at a certain frequency, and a quartz sand layer is provided above the catalyst to prevent the catalyst particles from flying away under the action of a strong electric field.

4. The novel plasma in-situ DRIFTS reaction cell according to claim 1 is characterized in that: Infrared light enters from an optical window (5), is reflected at the sample pool (3), and then exits from another optical window (5).

5. The novel plasma in-situ DRIFTS reaction cell according to claim 1 is characterized in that: The optical window (5) is made of ZnSe or KBr, with a diameter of 15-25 mm and a thickness of 2-4 mm. The angle between the optical window (5) and the horizontal plane is 55-60 degrees. A graphite gasket is used to seal the optical window (5) and the dome (2). The thickness of the graphite gasket is 0.1-0.2 mm. A heating wire is arranged around the optical window (5).

6. The novel plasma in-situ DRIFTS reaction cell according to claim 1 is characterized in that: The base (1) is made of a high-performance dielectric material, with a diameter ranging from 30 to 50 mm and a height of 20 to 30 mm. The dome (2) is made of stainless steel or gold-plated material, with a diameter matching that of the base and a height of 20 to 30 mm. The base (1) and the dome (2) cooperate to form an overall structure with a height of 40 to 60 mm. The dome (2) has a thickness of 2-4 mm and the inner surface is electrochemically polished or plasma sprayed.

7. The novel plasma in-situ DRIFTS reaction cell according to claim 1 is characterized in that: The high-voltage electrode (4) is made of platinum, tungsten or 316L stainless steel, with a diameter of 0.5-1.5 mm and a length of 30-50 mm; an insulating sleeve is provided on the surface of the high-voltage electrode (4); The top of the high voltage electrode (4) is 3-5 mm below the catalyst surface and deviates from the central axis of the sample pool (3) by 0.5-1 mm.

8. The novel plasma in-situ DRIFTS reaction cell according to claim 7 is characterized in that: The high voltage electrode (4) adopts a spherical or hemispherical electrode head with a diameter of 1.5-2.5 mm; The surface of the high voltage electrode (4) is treated by micron-level plasma spraying to form a porous structure with a thickness of 10-50 μm.

9. The novel plasma in-situ DRIFTS reaction cell according to claim 1 is characterized in that: The reaction tank is designed with a spiral gas distribution groove with a width of 0.5-1mm and a depth of 0.5-1mm; A miniature photodetector is arranged inside the reaction pool.

10. The novel plasma in-situ DRIFTS reaction cell according to claim 1 is characterized in that: The base (1) is provided with a dome limiting groove (1-5) matching the dome (2), the dome limiting groove (1-5) is provided with an O-ring groove (1-6), and the O-ring groove (1-6) is provided with a high-temperature and pressure-resistant O-ring.

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